1. Field of the Invention
The present invention relates generally to compositions for topical application and, particularly, to pigmented compositions for application to the skin. More particularly, the present invention relates to a pigmented vitamin C composition.
2. Description of the Prior Art
Ascorbic acid, also known as vitamin C, has long been recognized as a substance benefiting the skin. However, ascorbic acid has also long been recognized as unstable. For example, although ascorbic acid is readily soluble in water, rapid oxidation occurs in substantially aqueous media. In addition, the solubility of ascorbic acid in anhydrous media has been reported to be relatively poor. Moreover, ascorbic acid is sensitive to the influence of light and oxygen.
The instability of ascorbic acid runs counter to the effectiveness that is sought. Furthermore, it can be a source of unpleasantness for the user. For example, the instability of the active substance may lead to color and/or odor changes in the composition containing it.
Heretofore, one way of dealing with the instability of ascorbic acid is stabilizing it in an acidic medium. However, cosmetic compositions that stabilize ascorbic acid in an acidic medium invite a different set of problems. For example, the incorporation of a pigment into such an acidic medium becomes very difficult.
A pigment is a water-insoluble dye that may be used in cosmetic compositions. Pigments have several beneficial characteristics when used in cosmetic compositions. For example, pigments are inexpensive, provide ultraviolet light protection, and produce vibrant colors. However, pigments hydrolyze under acidic conditions. Hydrolysis leads to the breakdown and discoloration of the pigments. Accordingly, the cosmetic composition discolors.
Thus, there is a need for a cosmetic composition that stabilizes ascorbic acid and also incorporates a pigment.
It is an object of the present invention to provide a cosmetic composition having a vitamin, C component and a pigment.
It is another object of the present invention to provide such a composition that stabilizes both the vitamin C component and the pigment.
It is still another object of the present invention to provide such a composition that is cosmetically and aesthetically acceptable.
It has been unexpectedly discovered that a vitamin C component may be stabilized in a substantially aqueous phase of an emulsion that has a pigment in a substantially non-aqueous phase. Such an emulsion is both cosmetically and aesthetically acceptable.
The present invention is a composition having a vitamin C component in an emulsion. The phrase xe2x80x9cvitamin C component,xe2x80x9d as used herein, means vitamin C, and its derivatives and mixtures thereof.
The present invention is an emulsion having a substantially aqueous phase and a substantially non-aqueous phase. It has been unexpectedly discovered that such an emulsion may effectively sequester and, thus, stabilize both a vitamin C component and a pigment. The vitamin C component is substantially or, more preferably, completely sequestered and stabilized within the substantially aqueous phase. The pigment is substantially or, more preferably, completely sequestered within the substantially non-aqueous phase and, thus, from the aqueous phase.
The substantially aqueous phase is about 5 percent by weight (wt. %) to about 75 wt. % of the total weight of the composition. More preferably, the substantially aqueous phase is about 20 wt. % to about 50 wt. %, and most preferably about 30 wt. % to about 50 wt. % of the total weight of the composition.
The vitamin C component is dispersed in the substantially aqueous phase of the present invention. The vitamin C component is preferably present in an amount about 0.04 wt. % to about 20 wt. % of the total weight of the composition. More preferably, the vitamin C component is about 0.05 wt. % to about 7 wt. %, and most preferably about 0.075 wt. % to about 5 wt. %, of the total weight of the composition. Preferably, the vitamin C component includes vitamin C (ascorbic acid). More preferably, the vitamin C component is vitamin C.
The present invention can utilize the vitamin C preparations disclosed in and commonly assigned U.S. patent application Ser. No. 09/150,806, filed on Sept. 10, 1998, now U.S. Pat. No. 6,299,889 for xe2x80x9cStable Ascorbic Acid Preparation for Topical Use,xe2x80x9d the entirety of which is incorporated herein by reference.
One example of such a vitamin C preparation includes about 0.1 to about 16 wt. % ascorbic acid, about 20 to about 85 wt. % polyhydric alcohol, about 0.3 to about 25 wt. % organic carbonate, about 0.1 to about 12 wt. % water, and optionally, about 5 to about 38 wt. % monohydric alcohol, and about 0.01 to about 3 wt. % hydroxyalkyl cellulose. More preferably, an example of such a vitamin C preparation has about 8 wt. % to about 10 wt. % ascorbic acid, about 25 wt. % to about 35 wt. % monohydric alcohol, about 35 wt. % to about 45 wt. % polyhydric alcohol, about 0.1 wt. % to about 1 wt. % hydroxyalkyl cellulose, about 1 wt. % to about 10 wt. % organic carbonate, and about 8 wt. % to about 12 wt. % water.